Process for producing color filter

ABSTRACT

The present invention provides a photopolymerizable composition for a color filter containing an addition-polymerizable compound having at least one ethylenically unsaturated double bond, a photopolymerization initiator and the oxide of at least one metal selected from the group consisting of Cu, Fe, Mn, Cr, Co, Ni and Al and being substantially free from any halogen atom; and a process for producing a color filter. The photopolymerizable compositions for a color filter makes it possible to form a color filter having good heat resistance and high electrical insulation resistance and have high storage stability.

FIELD OF THE INVENTION

The present invention relates to a novel photopolymerizable compositionfor a color filter and a process for producing the color filter. Moreparticularly, it relates to a photopolymerizable composition which issuitable for manufacturing a spectral filter of each color such as blue,green and red, and a black matrix for a plasma display, a liquid crystaldisplay, etc. and which has excellent heat resistance, high electricalinsulation resistance and high storage stability, and a process forproducing a color filter with the use of the composition.

BACKGROUND OF THE INVENTION

In manufacturing a display device such as a plasma display and a liquidcrystal display, it has been a practice to use spectral filters ofvarious colors such as blue, green and red for spectrally classifyingback light, etc. or to provide a black filter as a black matrix toenhance the contrast. To produce these color filters, use is made ofphotopolymerizable compositions for color filters containing variousorganic color pigments such as phthalocyanine pigments and azo pigmentsor light-screening pigments such as carbon black. Color filters areproduced by applying the above-mentioned photopolymerizable compositionsfor color filters, which each has been preferably dissolved in asolvent, on substrates, and drying the same followed by pattern-makingby photolithography.

In recent years, it has been desired to use plasma display devices(hereinafter referred to simply as “PDP”) in practice. This is becausePDPs are usable as displays having an emission luminance comparable tothat of CRT displays and a relatively simple structure, which makes itpossible to provide large-scaled PDPs and compact apparatuses. It isexpected that PDPs provided with color filters of blue, green and red ora black matrix can show an enhanced contrast similar to that of CRTdisplays. However, the process for manufacturing PDPs includes the stepof baking at a temperature of 350 to 750° C. at which the conventionalphotopolymerizable compositions containing organic pigments or carbonblack as the major components would undergo decomposition orvolatilization of the pigments or carbon black. Thus, it is difficult toform any satisfactory color filters. To solve this problem, attemptshave been made to add inorganic pigments to photopolymerizablecompositions for color filters so as to impart heat resistance thereto.In these cases, however, there arises another problem that thephotopolymerizable compositions containing inorganic pigments would gelwithin a short period of time, thus showing poor storage stability.

SUMMARY OF THE INVENTION

Under these circumstances, the present inventors have conductedextensive studies. As a result, they have found out that the rapidgelation of the above-mentioned photopolymerizable composition for acolor filter is caused by the presence of halogen atoms and aphotopolymerizable composition for a color filter which is substantiallyfree from any halogen atom can achieve good heat resistance, highelectrical insulation resistance and high storage stability, thuscompleting the present invention.

Accordingly, an object of the present invention is to provide aphotopolymerizable composition for a color filter which has good heatresistance, high electrical insulation resistance and high storagestability.

Another object of the present invention is to provide a process forproducing a color filter by using the photopolymerizable composition fora color filter.

DETAILED DESCRIPTION OF THE INVENTION

To achieve the above-mentioned objects, the present invention relates toa photopolymerizable composition for a color filter containing anaddition-polymerizable compound having at least one ethylenicallyunsaturated double bond, a photopolymerization initiator and metaloxide(s) as a coloring material and being substantially free from anyhalogen atom and a process for producing a color filter with the use ofthe same.

The term “an addition-polymerizable compound having at least oneethylenically unsaturated double bond” (hereinafter referred to simplyas an “ethylenic compound”) as used herein means a compound having atleast one ethylenically unsaturated double bond to causeaddition-polymerization and curing under the action of thephotopolymerization initiator, when the photopolymerizable compositionis irradiated with energy radiation. Namely, it means a monomer havingthe above-mentioned ethylenically unsaturated double bond or a polymerhaving the ethylenically unsaturated double bond in the side chain orthe main chain thereof. The term “monomer” as used herein means those tobe distinguished from “polymer” and includes not only “monomers” in anarrow sense but also dimers, trimers and oligomers. Examples of themonomer include unsaturated carboxylic acids; esters of aliphatic(poly)hydroxy compounds with unsaturated carboxylic acids; esters ofaromatic (poly)hydroxy compounds with unsaturated carboxylic acids;esters obtained by esterification reaction of an unsaturated carboxylicacid, a polyvalent carboxylic acid and a polyvalent hydroxy compoundsuch as the above-mentioned aliphatic (poly)hydroxy compounds andaromatic (poly)hydroxy compounds; unsaturated carboxylic acid amides;and unsaturated carboxylic acid nitrites. More particularly, usefulexamples thereof include methyl acrylate, methyl methacrylate, ethylacrylate, ethyl methacrylate, isobutyl acrylate, isobutyl methacrylate,2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, ethylene glycolmonomethyl ether acrylate, ethylene glycol monomethyl ethermethacrylate, ethylene glycol monoethyl ether acrylate, ethylene glycolmonoethyl ether methacrylate, glycerol acrylate, glycerol methacrylate,acrylamide, methacrylamide, acrylonitrile, methacrylonitrile,2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, benzyl acrylate,benzyl methacrylate, ethylene glycol diacrylate, ethylene glycoldimethacrylate, triethylene glycol diacrylate, triethylene glycoldimethacrylate, tetraethylene glycol diacrylate, tetraethylene glycoldimethacrylate, butylene glycol dimethacrylate, propylene glycoldiacrylate, propylene glycol dimethacrylate, trimethylolethanetriacrylate, trimethylolethane trimethacrylate, trimethylolpropanetriacrylate, trimethylolpropane trimethacrylate, tetramethylolpropanetetracrylate, tetramethylolpropane tetramethacrylate, pentaerythritoltriacrylate, pentaerythritol trimethacrylate, pentaerythritoltetracrylate, pentaerythritol tetramethacrylate, dipentaerythritolpentacrylate, dipentaerythritol pentamethacrylate, dipentaerythritolhexacrylate, dipentaerythritol hexamethacrylate, 1,6-hexanedioldiacrylate, 1,6-hexanediol dimethacrylate, cardoepoxy diacrylate,cardoepoxy dimethacrylate, the compounds in which the acrylate ormethacrylate in the above-exemplified compounds is replaced withfumarate, maleate, crotonate or itaconate, acrylic acid, methacrylicacid, fumaric acid, maleic acid, crotonic acid, itaconic acid,hydroquinone monoacrylate, hydroquinone monomethacrylate, hydroquinonediacrylate, hydroquinone dimethacrylate, resorcin diacrylate, resorcindimethacrylate, pyrogallol diacrylate, pyrogallol triacrylate,condensation products of diethylene glycol with acrylic acid or maleicacid, condensation products of diethylene glycol with phthalic acid,condensation products of pentaerythritol with methacrylic acid orterephthalic acid, condensation products of butanediol or glycerol withacrylic acid or adipic acid, ethylenebisacrylamide,ethylenebismethacrylamide, allyl esters such as diallyl phthalate, anddivinyl phthalate.

Examples of the polymers having the ethylenically unsaturated doublebond in the side chain or main chain thereof include polyesters obtainedby the polycondensation between unsaturated divalent carboxylic acidswith dihydroxy compounds; polyamides obtained by the polycondensationbetween unsaturated divalent carboxylic acids with a diamine; polyestersobtained by the polycondensation between itaconic acid,propylidenesuccinic acid or ethylidenemalonic acid with a dihydroxycompound; polyamides obtained by the polycondensation between itaconicacid, propylidenesuccinic acid or ethylidenemalonic acid with a diamine;phenol novolak type epoxyacrylate; phenol novolak typeepoxymethacrylate; cresol novolak type epoxy acrylate; cresol novolaktype epoxymethacrylate, bisphenol A type epoxyacrylate; bisphenol S typeepoxyacrylate; urethane acrylate oligomers; and urethane methacrylateoligomers. Also, use may be made therefor of polymers obtained byfurther reacting the above-mentioned epoxy(meth)acrylate resins withpolybasic acid anhydrides. Moreover, use can be made therefor ofpolymers having reactive functional groups (hydroxyl, haloalkyl, etc.)in side chains, for example, those obtained by reacting polyvinylalcohol, poly(2-hydroxyethyl methacrylate), polyepichlorohydrin, etc.with unsaturated carboxylic acids such as acrylic acid, methacrylicacid, fumaric acid, maleic acid, crotonic acid and itaconic acid. Amongall, it is particularly preferable to use acrylate or methacrylatemonomers therefor.

The ethylenic compound as described above can be used in an amount offrom 50 to 99 parts by weight per 100 parts by weight of the sum of theethylenic compound and the photopolymerization initiator. It is notpreferable that the content of the ethylenic compound is less than 60parts by weight, since the abrasion resistance and chemical resistanceof the film obtained after the exposure and curing are deteriorated.Furthermore, it is not preferable that the content thereof exceeds 99parts by weight, since the sensitivity is sometimes lowered in such acase.

Triazine compounds have been frequently employed as aphotopolymerization initiator due to the high sensitivity thereof.However, the use of the compounds containing a trihalomethane groupcauses gelation and is not preferred. Examples of thephotopolymerization initiator usable in the present invention include1-, hydroxycyclohexyl phenylketone,2,2-dimethoxy-1,2-diphenylethan-1-one,2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one,2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one,2-hydroxy-2-methyl-1-phenylpropan-1-one, 2,4,6-trimethylbenzoyldiphenylphosphine oxide,1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one,2,4-diethylthioxanthone, 2,4-dimethylthioxathone,3,3-dimethyl-4-methoxybenzophenone, benzophenone,1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one,1-(4-dodecylphenyl)-2-hydroxy-2-methylpropan-1-one,4-benzoyl-4′-methyldimethylsulfide, 4-dimethylamninobenzoic acid, methyl4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, butyl4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate, 2-isoamyl4-dimethylaniinobenzoate, 2,2-diethoxyacetophenone, benzyl dimethylketal, benzyl-β-methoxyethyl acetal,1-phenyl-1,2-propanedione-2-(o-ethoxycarbonIyl)oxime, methylo-benzoylbenzoate,bis(4-dimethylaminophenyl)ketone,4,4′-bisdiethylaminobenzophenone, benzyl, benzoin, benzoin methyl ether,benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether,benzoin isobutyl ether, benzoin butyl ether,p-dimethylaminoaceto-phenone, thioxanthone, 2-methyl thioxathone,2-isopropyl thioxathone, dibenzosuberone,α,α-dichloro-4-phenoxyacetophenone and pentyl-4-dimethylaminobenzoate.Amaong all, 2-benzyl-2-dimethylamino-1-(4- morpholinophenyl)butan-1-oneis particularly preferred from the viewpoints of sensitivity andstability.

The photopolymerizable composition for a color filter of the presentinvention may further contain, as a coloring material, oxides, sulfides,sulfates or carbonates of various metals such as Cu, Fe, Mn, Cr, Co, Ni,Ti, V, Zn, Se, Mg, Ca, Sr, Ba, Pd, Ag, Cd, In, Sn, Sb, Hg, Pb, Bi, Siand Al. It is particularly preferable to use the oxide of at least onemetal selected from among Cu, Fe, Mn, Cr, Co, Ni and Al. Use of such ametal oxide makes it possible to form an excellent color filter and,moreover, provide a display device having a high electrical insulationresistance, suffering from little current leakage and consuming a lowelectric power. It is further preferable that the metal oxide has anaverage particle size of from 0.01 to 5 μm. When the average particlesize falls within the range as specified above, color filters, forexample, spectral filters of blue, green or red and black filters havingexcellent qualities can be produced. Even when baked at 350 to 750° C.,the photopolymerizable composition for a color filter of the presentinvention suffers from neither decomposition nor volatilization of themetal oxide and thus ensures the production of a color filter havingexcellent quality.

Particular examples of the above-mentioned metal oxide includeFe₂O₃.CuO, Fe₃O₄.CuO, MnO₂.CuO, CuO.Cr₂O₃, CuO.CoO, CuO.NiO,Fe₂O₃.MnO₂.CuO, Fe₃O₄.MnO₂.CuO, MnO₂.CuO.Cr₂O₃, MnO₂.CuO.CoO,MnO₂.CuO.NiO, Fe₂O₃.Fe₃O₄.MnO₂.CuO, Fe₂O₃.Fe₃O₄.MnO₂.CuO.Cr₂O₃,Fe₂O₃.Fe₃O₄.MnO₂.CuO.CoO, Fe₂O₃.Fe₃O₄.MnO₂.CuO.NiO,Fe₂O₃.Fe₃O₄.MnO₂.CuO.Cr₂O₃.CoO, Fe₂O₃.Fe₃O₄.MnO₂.CuO.Cr₂O₃.NiO, andFe₂O₃.FeO₃O₄.MnO₂.CuO.Cr₂O₃.CoO.NiO, though the present invention is notrestricted thereto. Among all, it is preferable to use Cu oxides, Feoxides or Mn oxides such as Fe₂O₃.MnO₂.CuO, Fe₃O₄.MnO_(z).CuO,Fe₂O₃.Fe₃O₄.MnO₂.CuO, Fe₂O₃.Fe₃O₄.MnO₂.CuO.Cr₂O₃,Fe₂O₃.Fe₃O₄.MnO₂.CUO.CoO, Fe₂O₃.Fe₃O₄.MnO₂.CuO.NiO,Fe₂O₃.Fe₃O₄.MnO₂.CuO.Cr₂O₃.CoO, Fe₂O₃.Fe₃O₄.MnO₂.CuO.Cr₂O₃.NiO, andFe₂O₃.Fe₃O₄.MnO₂.CuO.Cr₂O₃.CoO.NiO.

The above-mentioned metal oxide can be used generally in an amount offrom 10 to 90 parts by weight per 100 parts by weight of the totalamount of the ethylenic compound, the photopolymerization initiator andthe metal oxide.

The photopolymerizable composition for a color filter can furthercontain a low-melting glass. Examples of the low-melting glass includephosphorus compounds such as P₂O₅, H₃PO₃, H₂PO₄, H₄P₂O₇,(RO)₃P, (PO)₂,POH,(RO)₃PO, RP(OR′)₂, R₂P(OH), R₂PO(OH) and RPO(OH)₂; boron compoundssuch as B₂O₃, H₃BO₃, (RO)₃B, RB(OR′)₂, R₂BOR′, RB(OH)₂, R₂BOH,R₃B,(RBO)_(n) and (RB₂)₂O; arsenic compounds such as H₂AsO₃, H₃AsO₄,(RO)₃As,(RO)₂AsOH, RAs(OR′)₂, RAsH₂, R₂AsH, R₃As, RAsO, (R₂As)₂O, R₃AsO,RAs(OH)₂, RAsO(OH)₂ and R₂As(OH); antimony compounds such as H₃SbO₄,H₃SbO₃, H₃Sb₂O₇, H₃SbO₁₀, (RO)₃Sb, (RO)₂Sb(OH), RSb(OR′)₂, R₅Sb, RSbO,(R₂Sb)₂O, R₃SbO, R₂SbO(OH) and RSbO(OH)₂; zinc compounds such asZn(OCOCH₃) and Zn(OR)₂; lead compounds such as Pb(OCOCH₃)₄ and Pb(OR)₄;and gallium compounds such as RGa(OH) and RGa(OH)₂ (wherein R and R′represent each an alkyl or aryl group); and mixtures thereof. After thecompletion of the baking, this low-melting glass serves as a binder forthe metal oxide to thereby give a rigid color filter.

The photopolymerizable composition for a color filter of the presentinvention is substantially free from any halogen atom. The term“substantially free from any halogen atom” means that when measured byusing a polarized Zeeman atomic absorption spectrometer, the content ofhalogen atoms is 0.001 part by weight or less per 100 parts by weight ofthe metal oxide. Furthermore, it is preferred that when measured byusing a mass spectrometer, the content of halogen atoms covalentlybonded to carbon atoms is 0.0001 part by weight or less per 100 parts byweight of the metal oxide. Needless to say, it is desirable that thephotopolymerizable composition contains no halogen atom. However,halogen atoms, which are contained as impurities in each component,should be eliminated as far as possible. The photopolymerizablecomposition for a color filter of the present invention, which issubstantially free from any halogen atom as described above, would notgel within a short period of time and, therefore, shows a high storagestability. The halogen atoms as described above include fluorine,chlorine, bromine, iodine and astatine atoms.

The photopolymerizable composition for a color filter of the presentinvention may further contain a polymer binder in order to improve theapplication properties thereof and the physical properties afterphoto-curing. A suitable binder can be selected depending on the factorto be improved, for example, compatibility, film-forming properties,developing properties, adhesiveness, etc. Particular examples of thepolymer binder include polymers or copolymers prepared by polymerizingor copolymerizing monomers selected from acrylic acid, methacrylic acid,methyl acrylate, methyl methacrylate, ethyl acrylate, ethylmethacrylate, propyl acrylate, propyl methacrylate, isopropyl acrylate,isopropyl methacrylate, n-butyl acrylate, n-butyl methacrylate,tert-butyl acrylate, tert-butyl methacrylate, 2-hydroxyethyl acrylate,2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropylmethacrylate, benzyl acrylate, benzyl methacrylate, phenoxy acrylate,phenoxy methacrylate, isobornyl acrylate, isobornyl methacrylate,glycidyl methacrylate, styrene, acrylamide, methacrylamide,acrylonitrile, methyacrylonitrile, vinyl chloride and vinylidenechloride; modified acidic cellulose derivatives having carboxyl group inside chain; polyethylene oxide; polyvinyl pyrrolidone; a copolymer ofvinylidene chloride and vinyl acetate; a copolymer of a chlorinatedpolyolefin and vinyl acetate; a copolymer of vinyl chloride and vinylacetate; polyvinyl acetate; a copolymer of acrylonitrile and butadiene;polyvinyl alkyl ethers; polyvinyl alkyl ketones; polystyrene;polyamides; polyurethane; polyethylene terephthalate isophthalate;acetyl cellulose; and polyvinyl butyral. It is particularly preferableto use a monomer having carboxyl group (acrylic acid, methacrylic acid,etc.) as a comonomer so as to improve the developing properties with analkaline aqueous solution. It is preferable that the content of theacrylic acid, methacrylic acid, etc. as described above amounts to 5 to40% by weight based on the total comonomers. Also, it is preferable touse carboxymethyl cellulose, carboxyethyl cellulose and carboxypropylcellulose or cellulose resins prepared by reacting the hydroxyl groupsof hydroxymethyl cellulose, hydroxyethyl cellulose or hydroxypropylcellulose with polybasic acid anhydrides.

The content of the polymer binder is generally 400 parts by weight orless, preferably 200 parts by weight or less, per 100 parts by weight ofthe total amount of the ethylenic compound, the photopolymerizationinitiator and the metal oxide.

To improve the application properties, the photopolymerizablecomposition for a color filter of the present invention may furthercontain a solvent. Examples of the solvent include ethylene glycolmonomethyl ether, ethylene glycol monoethyl ether, ethylene glycolmonopropyl ether, ethylene glycol monobutyl ether, ethylene glycoldimethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropylether, propylene glycol monomethyl ether, propylene glycol monoethylether, propylene glycol monopropyl ether, propylene glycol monobutylether, propylene glycol dimethyl ether, propylene glycol diethyl ether,diethylene glycol monomethyl ether, diethylene glycol monoethyl ether,diethylene glycol dimethyl ether, diethylene glycol diethyl ether,ethylene glycol monomethyl ether acetate, ethylene glycol monoethylether acetate, ethylene glycol monopropyl ether acetate, ethylene glycolmonobutyl ether acetate, propylene glycol monomethyl ether acetate,propylene glycol monoethyl ether acetate, propylene glycol monopropylether acetate, 2-methoxybutyl acetate, 3-methoxybutyl acetate,4-methoxybutyl acetate, 2-methyl-3-methoxybutyl acetate,3-methyl-3-methoxybutyl acetate, 3-ethyl-3-methoxybutyl acetate,2-ethoxybutyl acetate, 4-ethoxybutyl acetate, 4-propoxybutyl acetate,2-methoxypentyl acetate, 3-methoxypentyl acetate, 4-methoxypentylacetate, 2-methyl-3-methoxypentyl acetate, 3-methyl-3-methoxypentylacetate, 3-methyl-4-methoxypentyl acetate, 4-methyl-4-methoxypentylacetate, acetone, methyl ethyl ketone, diethyl ketone, methyl isobutylketone, ethyl isobutyl ketone, methyl carbonate, ethyl carbonate, propylcarbonate, butyl carbonate, benzene, toluene, xylene, cyclohexanone,methanol, ethanol, propanol, butanol, hexanol, cyclohexanol, ethyleneglycol, diethylene glycol and glycerol. Among all, it is preferable touse 3-methoxybutyl acetate therefor.

The content of the above-mentioned solvent is generally 1,000 parts byweight or less, preferably 500 parts by weight or less, per 100 parts byweight of the total amount of the ethylenic compound, thephotopolymerization initiator and the metal oxide.

In addition to the components as described above, the photopolymerizablecomposition for a color filter of the present invention may furthercontain a sensitizer, a thermal polymerization inhibitor, a plasticizer,a surfactant, a defoaming agent and other additives, if needed. Examplesof the sensitizer include xanthene dyestuffs such as Eosin B (C.I. No.45400), Eosin J (C.I. No. 45380), alcohol-soluble eosin (C.I. No.45386), cyanosin (C.I. No. 45410), Bengal rose, erythrosin (C.I.No.45430), 2,3,7-trihydroxy-9-phenylxanthen-6-one and rhodamine 6G;thiazine dyestuffs such as thionine (C.I. No. 52000), Azure A (C.I. No.52005) and Azure C (C.I. No. 52002); pyronine dyestuffs such as PyronineB (C.I. No. 45005) and Pyronine GY (C.I. No. 45006); and coumarincompounds such as 3-acetylcoumarin and 3-acetyl-7-diethylaminocoumarin.Examples of the thermal polymerization inhibitor include hydroquinone,hydroquinone monoethyl ether, p-methoxy phenol, pyrogallol, catechol,2,6-di-tert-butyl-p-cresol and β-naphthol. Examples of the plasticizerinclude dioctyl phthalate, didoecyl phthalate, triethylene glycoldicaprylate, dimethyl glycol phthalate, tricresyl phosphate, dioctyladipate, dibutyl cebacate and triacetyl glycerol. Examples of thesurfactants include anionic, cationic and nonionic surfactants ofvarious types. Examples of the defoaming agents include variousdefoaming agents such as silicone series and fluorine series.

Next, an example of the process for producing a color filter of thepresent invention will be described.

1) Preparation of Photopolymerizable Composition for Color Filter

To a photopolymerizable composition for color filter are added, ifneeded, a binder, a solvent, a sensitizer, a thermal polymerizationinhibitor, a plasticizer, a surfactant, a defoaming agent, etc. and theresultant mixture is well dispersed and kneaded in a triple roll mill, aball mill, a sand mill, a jet mill, etc.

2) Application of Photopolymerizable Composition for Color Filter

The photopolymerizable composition for a color filter prepared above isapplied onto a substrate the surface of which has been preliminarilycleaned. Examples of the substrate include those made of glass,polyethylene terephthalate, an acrylic resin, etc. To improve theadhesiveness of the photopolymerizable composition to the substrate, asilane coupling agent may be preliminarily added to thephotopolymerizable composition or applied on the substrate. To apply thephotopolymerizable composition for a color filter, use can be made of acontact transfer coating apparatus such as a roll coater, a reversecoater or a bar coater, or a non-contact transfer coating apparatus suchas a spinner or a curtain flow coater. To form a thick film, thecomposition is applied twice or more. Alternatively, several coatingapparatuses selected from among the above-mentioned one may be employedtherefor. After the application, the photopolymerizable composition fora color filter is allowed to stand at room temperature for several hoursto several days or in a hot-air heater or an infrared heater for severalten minutes to several hours to thereby remove the solvent therefrom.The coating film thus formed has a thickness of approximately from 1 to10 μm.

3) Exposure

After the formation of the coating film, it is exposed, via a negativemask, to actinic energy radiation such as UV rays, eximer laser, X-ray,γ-ray and electron radiations. The irradiation dose of the energyradiation preferably ranges from 30 to 2,000 mJ/cm², though it may varydepending on the components of the photopolymerizable composition.

4) Development

After the completion of the exposure, developing is performed bydipping, spraying, etc. with the use of a developer solution. As theliquid developer, use may be made of aqueous solutions of hydroxides,carbonates, bicarbonates, phosphates and pyrophosphates of alkali metals(lithium, sodium, potassium, etc.), primary amines (benzylamine,butylamine, etc.), secondary amines (dimethylamine, dibenzylamine,diethanolamine, etc.), tertiary amines (trimethylamine, triethylamine,triethanolamine, etc.), cyclic amines (morpholine, piperazine, pyridine,etc.), polyamines (ethylenediamine, hexamethylenediamine, etc.),ammonium hydroxides (tetraethylammonium hydroxide,trimethylbenzyl-ammonium hydroxide, tirmethylphenylbenzylammoniumhydroxide, etc.), sulfonium hydroxides (trimethylsulfonium hydroxide,diethylmethylsulfonium hydroxide, dimethylbenzylsulfonium hydroxide,etc.), choline, etc.

The production of a color filter for liquid crystal displays, etc. withthe use of the photopolymerizable composition of the present inventionis completed by the above-mentioned developing step. To produce a colorfilter for PDPs, however, the additional step of baking should befurther carried out.

5) Baking

After the completion of the developing and drying, the color filter thusformed is baked at a temperature of 350 to 750° C. Thus the componentsof the color filter other than the metal oxide are thermally decomposedand volatilized to give a color filter containing the metal oxide. Thisbaking step, whereby all organic matters are removed from the colorfilter, contributes to the provision of error-free PDPs.

As discussed above, the photopolymerizable composition for a colorfilter of the present invention is effective in manufacturing PDPs andliquid crystal displays. Moreover, the composition is well applicable tothe production of color filters of other display devices. Among all, thephotopolymerizable composition of the present invention is mostpreferable for manufacturing PDP.

To further illustrate the present invention in greater detail, and notby way of limitation, the following Examples will be given.

EXAMPLE 1

The components 1 to 6 as will specified below were dispersed and kneadedtogether in a ball mill for 2 hours to thereby give a photopolymerizablecomposition for a color filter.

(parts by weight) 1. Daipyroxide color #9560 (manufactured by 40Dainichiseika Colour & Chemicals Mfg. Co., Ltd.; Fe₂O₃.MnO₂.CuO-basedpigment) 2. Methacrylic acid/methyl methacrylate copolymer 15 (ratio byweight: 25/75 and weight-average-molecular weight: ca. 25000) 3.Trimethylolpropane triacrylate 9 4.2-Benzyl-2-dimethylamino-1-(4-morpholino- 3 phenyl)-butan-1-one(manufactured by Ciba- Geigy: IRGACURE 369) 5. diethylthioxanthone 1 6.3-methoxybutyl acetate 55

When measured with a polarized Zeeman atomic absorption spectrometer(manufactured by Hitachi., Ltd.), the photopolymerizable composition fora color filter thus obtained contained 0.0002 parts by weight of halogenatoms per 100 parts by weight of the metal oxide. When measured with amass spectrometer (GMSM; manufactured by Otsuka Electron Co., Ltd.),this composition contained 0.00005 parts by weight of halogen atomscovalently bonded to carbon atoms per 100 parts by weight of the metaloxide.

When the photopolymerizable composition for a color filter preparedabove was allowed to stand at ordinary temperature for 6 months, therearose no deterioration such as gelation. After allowing to stand for 6months, the photopolymerizable composition for a color filter wasapplied onto a glass substrate (thickness: 3 mm) having a clean surfaceby using a reverse coater (manufactured by Dainippon Screen Mfg. Co.,Ltd.) in such a manner as to give a dry film thickness of 2 μm and thendried at 80° C. for 1 minute. Next, it was entirely irradiated with 800mJ/cm² of UV rays and then baked in an electric oven at 540° C. for 30minutes. When the substrate was irradiated from behind with a three bandfluorescent lamp, it showed no color shading, which indicated that itwas an excellent black matrix. The OD (optical density) value of thecomposition indicating its light-screening properties was 2.5, while itselectrical insulation resistance determined with a High Resistance Meter4339 A (manufactured by Hewlett-Packard) was 8.51×10¹² Ω/□.

Similarly, the photopolymerizable composition for a color filter wasapplied on a glass substrate and dried. Then it was exposed to light viaa nega mask, developed at 25° C. for 90 seconds with the use of a 2%aqueous solution of sodium carbonate and baked. The black matrix thusobtained was an excellent one which showed neither defect, peeling nordiscoloration in the exposed part and no residue in the unexposed part.

COMPARATIVE EXAMPLE 1

The components 1 to 6 as will specified below were dispersed and kneadedtogether in a ball mill for 2 hours to thereby give a photopolymerizablecomposition for a color filter.

(parts by weight) 1. Daipyroxide color #9560 (manufactured by 40Dainichiseika Colour & Chemicals Mfg. Co., Ltd.; Fe₂O₃.MnO₂.CuO-basedpigment) 2. Methacrylic acid/methyl methacrylate copolymer 15 (ratio byweight; 25/75, and weight-average molecular weight: ca. 25000) 3.Trimethylolpropane triacrylate 9 4.2,4-bis-trichloromethyl-6-[di(ethoxycarbonyl- 3methyl)amino]phenyl-s-triazine 5. Diethylthioxanthone 1 6.3-Methoxybutyl acetate 55

When measured in the same manner as in Example 1, the photopolymerizablecomposition for a color filter thus obtained contained 1.26 parts byweight of halogen atoms per 100 parts by weight of the metal oxide.Similarly, this composition contained 1.26 parts by weight of halogenatoms covalently bonded to carbon atoms per 100 parts by weight of themetal oxide.

When the photopolymerizable composition for a color filter preparedabove was allowed to stand at ordinary temperature for 6 months, itunderwent gelation and, therefore, could not be used in producing acolor filter.

The photopolymerizable composition for a color filter of the presentinvention has high storage stability without causing gelation. The colorfilters produced by using the composition exhibits excellent heatresistance and high electrical insulation resistance. Therefore, thecomposition is suitable as a photopolymerizable composition forproducing spectral filters of various colors (blue, green, red, etc.)and a black filter for PDPs and liquid crystal displays, and isparticularly useful in PDPs.

While the invention has been described in detail and with reference tospecific examples thereof, it will be apparent to one skilled in the artthat various changes and modifications can be made therein withoutdeparting from the spirit and scope thereof.

What is claimed is:
 1. A process for producing a color filter whichcomprises applying a photopolymerizable composition for a color filter(1) containing an addition-polymerizable compound having at least oneethylenically unsaturated double bond, a photopolymerization initiatorand metal oxide(s) and (2) being substantially free from any halogenatom on a substrate; drying the same; then selectively irradiating thesame with actinic radiation; and developing to thereby form a desiredcolor pattern.
 2. The process for producing a color filter as claimed inclaim 1, wherein, after the formation of said desired pattern, baking isfurther performed at a temperature of 350 to 750° C.